WCF: Building RESTful Services

Steve MaineSenior Program ManagerMicrosoft Corporation

Source: Pingdom.com

1993:Web == Content

The Browser Generic client experience

URI’s Addressing and identification

HTML Common presentation format

Hyperlinks Anarchic interconnectivity

HTTP GET Common operation everything supports

Content-Driven Web Architecture

2008:Web == Content + Capabilities

Capability-Enabled Web Architecture

Rich Browser Clients Programmability via script or plugins

HTTP Baseline application protocol Common set of operations + status codes

Domain-neutral data-oriented formats JSON, Atom/Atom Publishing Refine to support domain-specific schemas

Presentation formats HTML, CSS

RESTful Tenents

The Web is a graph of linked Resources Resources are identified by URI’s Resources support a fixed set of operations

In practice, these are defined by HTTP Applications follow links

to achieve late binding

REST is an architectural style, not a specification

REST Continuum

Well Constructed URIs

HTTP Verbs GET – Fetch PUT – Update/Insert DELETE – Delete POST – Append

Standard Representations

RESTfullness

POST to 1 URI OKQuerystrings OK

HTTP Verbs GET – Fetch POST – Overloaded

AJAX Services POX OK

Purists Pragmatists

AJAX Services with WCF

demo

webHttpBinding

New “web-friendly” WCF Binding in Fx 3.5 Allows for the development of RESTful services Does not use SOAP envelopes HTTP and HTTPS Transports Only

Supports several wire formats: XML JSON Binary (streams)

WebServiceHost

Specialized SerivceHost for RESTful services Eliminates need for lots of configuration Automatically configures address, binding,

contract Optimized for single-endpoint services Use from .svc file:

<%@ ServiceHost Language="C#" Debug="true" Service="Caching1.FeedService" Factory=“System.ServiceModel.Activation.WebServiceHostFactory” %>"%>

[WebGet] And [WebInvoke]

Binds a WCF operation to URI space and HTTP method

Indicate the HTTP Method for the operation WebGet – Don’t make me write it WebInvoke – All verbs other than GET (Method

parameter takes in the name of the Verb) Other Parameters

BodyStyle – Indicates whether the Request/ Response are wrapped or not

RequestFormat – Json or Xml ResponseFormat – Json or Xml UriTemplate – Rich binding to URI

UriTemplate

String that allows you to define the structure of the URI, as well as to define “Holes” The “Holes” are variables You Bind the template with parameters to

fill the holes

{productId} hole / variable gets bound to productId parameter in operation

[OperationContract][WebGet(UriTemplate=“product/{productId}")]Product GetProduct(int productId);

Variable

WCF REST Starter Kit

announcing

WCF REST Starter Kit

Microsoft.ServiceModel.Web.dll New features supporting RESTful services

Visual Studio 2008 Templates REST Collections/Singleton Services Atom Feed/Atom Publishing Protocol HTTP/POX Services

REST Samples Codeplex Project

Released at PDC Written by WCF team Features may be included in .NET 4.0

The REST 0f WCF

demo

What We've Talked About Today

REST and the “zen” of the web WCF features for REST scenarios

[WebGet] + [WebInvoke] UriTemplate WebHttpBinding And many more…

The WCF REST Starter Kit Available today at http://msdn.com/wcf/rest

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© 2008 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market

conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

WebGet/WebInvoke Examples

[OperationContract][WebInvoke( Method=“PUT", ResponseFormat=WebMessageFormat.Json, UriTemplate=“product/{productId}")]Product UpdateProduct(int productId, product p);

[OperationContract][WebGet( ResponseFormat=WebMessageFormat.Json, UriTemplate=“product/{productId}")]ProductData GetProduct(int productId);

WebProtocolException

CLR Exception that can be turned into HTTP status code on the wire

Can optionally carry detail information for display in the browser

[OperationContract, WebGet]Stream EchoText(string text){ if( text == null ) throw new WebProtocolException( HttpStatusCode.BadRequest ); . . .}

AdapterStream

Used when you want a Stream or TextWriter but don’t have one handy

[OperationContract, WebGet]Stream EchoText(string text){ return new AdapterStream( textWriter => { textWriter.WriteLine("You said: "); textWriter.WriteLine(text); textWriter.Flush(); }, Encoding.UTF8);}

Request Interceptors

MessageInspectors at the channel layer Think of them like a per-service pipeline Arbitrary message manipulation prior to

dispatch; can prevent dispatch too

public class XHttpMethodOverrideInterceptor:RequestInterceptor {

public override void ProcessRequest(ref RequestContext

requestContext) {

//Change the HTTP method used for dispatch based on

//the X-HTTP-Method-Override header }}

[WebCache]

Integrates WCF operations with ASP.NET caching (requires ASP.NET Compat Mode)

Cache profile stored in Web.config[OperationContract, WebGet][WebCache(CacheProfileName="CacheFor1Min")]public Atom10FeedFormatter GetFeed(int i) { … }

<system.web> <caching> <outputCacheSettings> <outputCacheProfiles>

<add name="CacheFor1Min" duration="60" enabled="true" location="Any" varyByParam=“i"/>

</outputCacheProfiles> </outputCacheSettings> </caching> </system.web>

ASP.NET Authentication Support

“It just works” with ASP.NET Full support for Membership + Roles Requires ASP.NET Compatibility Mode

[OperationContract, WebGet][PrincipalPermission(SecurityAction.Demand, Role=“admin")]SampleResponseBody GetData(int i, string s)